Fight trolls, ban IPs

What is a good way to fight trolls apart from protecting the room with a password/authentication?
Is there a way to ban certain IPs? Kicking the user as a moderator over and over is no really good solution.

If you know the IPs, simply restrict in iptables.

@Prashanth yea - but this needs access to the server. And not all moderators should have access there. I am searching for a solution on moderator level. Thanks for the answer though. Should have been more clear with the question.

Without any server support there is nothing a moderator can currently do since they won’t know the IP of the attacker anyway.

Setting a password or enabling the lobby is the way to go here.